The present invention relates generally to folding bed frame structures and, more particularly, to folding bed frames of the type specially adapted for opening and folding articulation from and into the enclosure of a sofa frame or the like.
Convertible sofa beds having widely varying folding bed frame structures are in common use. Characteristically, the folding bed frames of such sofa beds are provided with a plurality of bed sections pivotally connected in end-to-end relation and operatively associated with a linkage arrangement for mounting within the rectangular enclosure of a sofa bed frame defined by its side frame members, which normally comprise the sofa armrests, its sofa back and a front rail, to be articulable between a folded or retracted condition stored within the sofa frame enclosure and a horizontally extended condition disposed and extending outwardly from the enclosure over and beyond the front rail of the sofa frame.
Over the years, substantial activity has been devoted to the improvement of folding bed frame structures of this type, generally toward the common objective of providing a simple linkage arrangement which is compactly foldable and which requires a minimal amount of space for articulating the bed sections into and out of the enclosure of the sofa frame. While contemporary sofa bed frame structures substantially satisfy these objectives, there remain certain disadvantages which are common to most conventional bed frame structures. One such disadvantage is the dangerous tendency of a sofa bed frame structure, when fully extended for sleeping, to tilt upwardly at its foot end section whenever the weight of a person or persons supported on the bed frame structure is concentrated at the opposite head end section, thereby posing a potential risk of injury. An additional disadvantage of conventional sofa bed frame structures is the provision of a transverse mattress support bar extending across the width of the intermediate primary load-bearing section of the structure. While such mattress support bar is generally considered necessary or desirable to provide load bearing support for the mattress, this bar in most conventional sofa bed frame structures is noticeably felt by users sleeping on the sofa bed in its extended position and thereby interferes with the comfortability of the sofa bed.